Anaplasma platys (Apl) is an obligate intracellular bacteria that infects platelets and causes a cyclic thrombocytopenia in the dog. The dog appears, at this time, to be the only species affected by this rickettsial agent, and the disease is most likely transmitted by the Rhipicephalus spp of ticks. Apl was first reported in the United States in 1978 and has since been reported in Europe, Asia, South America, the Middle East, Australia, and Africa. Because of the common vector, Apl infection is often found as a co-infection with Ehrlichia canis. The ability of the organism to produce clinical disease in the dog appears to vary with geography, suggesting that strain differences may contribute to virulence. Apl is related to another Anaplasma species known to cause clinical disease in the dog, Anaplasma phagocytophilum (Aph). Aph is capable of infecting a wide range of mammals, including humans, and can produce significant morbidity. Clinical signs are usually non-specific and include anorexia, lethargy, lameness, fever, and thrombocytopenia. Aph is transmitted by the Ixodes spp of ticks and infections have been reported throughout the United States, the UK, and Europe.
Current diagnostic tests that attempt to distinguish Aph and Apl have limited specificity. PCR for Aph and Apl using 16SrRNA has also had problems with specificity. Therefore, PCR assays for specific detection of Apl are needed in the art. Additionally, serological tests for Apl that use Aph polypeptides or antibodies specific for Apl tend not to detect all instances of Apl infection or exposure. Therefore, serological tests that more accurately detect Apl are needed in the art.